j0rd4n

fyi, i just replaced the spark plugs...



right now i'm running with no thermostat (waiting to hear back from mazda dealer on availability of a thermostat) so the coolant is (assumedly) at full force all the time, and i think it is because it takes a looonng time for the temperature gauge to start moving up. well when it does, it'll sit around 1/8th up the gauge at idle (though my idle seems to sit between 1500-1250 which is weird because before I changed the plugs it would drop down to <1000).



so i let it idle for about 10min (i want it to warm up, seeing if it'll overheat) and it doesn't, so i take it down the street and fill the tires (they were at 25psi when i got it, needs 35 according to the tire!) with air. total i drive about 10 miles so i can see if it'll overheat (and i'm pushing it a good bit at times), and it seems fine (it never goes over 1/3). well i pull onto the dirt road my mom lives on, so i gotta slow down to ~15mph. all of a sudden i see it start creeping up. she lives about 3/4mi to 1mi down this road, so by the time i get back to the house, it's near 3/4, and creeping up a little bit at a time. i park it and let it sit there, and it doesn't go down.



i turn it off, and i can hear it bubbling. i check the overflow reservoir, and it's almost completely full. well, i let it cool down, and it sucked the overflow back into the system (lower temp=lower pressure or whatever). this is better than before i backflushed it since last time it was spewing water out of the overflow.



does anyone know what the problem could be now??? could it be due to my lack of thermostat? could it be that i used 5w40 oil and i needed something a little heavier for better cooling?



when i did the backflush and clean, i only drained the radiator each time. should i also drain the motor? i'm willing to backflush again if that could be the issue...



please help!

KarynKathryn

That is just what mine did. On mine it was the early stages of coolant seal failure....compression leaking into the coolant chamber and blowing the water out the overflow bottle

Karyn

j0rd4n

coolant seal failure, eh? can you elaborate on where/what this is? i'm a little confused, and is it easy to fix

hillbilly

5w-40 shouldnt cause it to over-heat at all, but 20w50 is whats reccomended for summertime. and oil does account for something like 20% of cooling... but I dont think thats causing the issues.



the lack of a thermostat could be whats causing the overheating but more troubleshooting is needed first.

reason is, the thermostat actually restricts the flow of the coolant through the radiator, giving it more time to cool before going back into the engine. if the radiator cant dissipate enough heat from the water before sending it back into the block its going to get hotter and hotter and so on. (like when you slowed down on the dirt road... less air through the radiator) a trick from the backyard might be to cut out the center (spring and everything) leaving that dime sized hole and put whats left of the thermostat back in (its pretty much a restrictor plate at this point)... not the correct wayto do things, but atleast we're imitating a thermostat here (might take longer to warm up in the mornings too)



the coolant seal issue (very likely but dont panic yet): between every rotor housing lies two coolant seals (inner and outter) if the inner is blown (melted) compression is going to leak from the combustion chamber into the water jacket pushing the coolant out the overflow (due to the increased pressure in the cooling system) and at the same time is going to push hot air in (hence the overheating). its not the easiest fix, but its do-able. You can get a new seal from someplace like atkins rotary for pretty cheap, but I would just reccomend getting the entire rebuild kit while you're there as its going to require a complete (or mostly complete, depending on which rotor the seal is blown) teardown of the engine.

-first do a compression check though (rotaryressurection I think has a good write up on this if you're not familiar) if the compression #'s read low (70,70,70) its a seal, if they read normal then we start looking elsewhere (waterpump, radiator, thermostat etc)

hillbilly

ps

when my coolant seal went, I could pull the plugs and see water form around the spark plug hole (just a minute ammount that when wiped with a finger would turn grey cuz of the little bit of grease there too) thought that might be an easy (but not the most deffinite) check for you too

j0rd4n

thx for the replies. the next time i'm at home (college now) i'll do a compression test and see what i get. perhaps that's why sometimes there's white smoke coming out the back if i let it sit overnight? i know there's a small leak somewhere, as i can see the accumulation on the bottom of the motor and oil pan, but i think that's just because of an old upper radiator hose and clamp, which will be replaced (already replaced lower rad hose) with the heater hoses.



i think it's about time for a rebuild anyway. i just need to save up money for the kit (i think i've read that the $1000 is worth the extra cost over the $500 one that atkins rotary offers?) as well as some of the tools i'll need (engine stand? tools to pull everything? the fsm seems to list a lot of custom tools for doing some of this stuff), so hopefully i can start a rebuild around mid-june after i pay off my credit card and have a few bucks to toss at it. that's when i figure i'll also give everything a good cleaning (there's lots of grim and grease and gunk built up around the motor) and replace worn motor mounts, etc.